1. Field of the Invention
The present invention relates to a technical field of stereoscopic display, more particularly, relates to an active barrier, a method for producing the active barrier, a display apparatus and an active shutter glasses.
2. Description of the Related Art
An ordinary display apparatus generally displays a scene in a two-dimension (2D) display mode and cannot represent information about a depth of field of the scene. With the development of the computer technology and the display technology, three-dimension (3D) display technology becomes a research focus of the display field.
Hereafter, it will describe the basic principle of the 3D display technology. When a viewer receives pictures from the same scene with left and right eyes, the pupil distance between the left and right eyes causes a position difference, therefore, the pictures formed on the retinas of the left and right eyes of the viewer have a slight difference, and this slight difference is referred as binocular parallax. The two slightly different pictures constitute a stereo picture pair, and the stereo picture pair produces a stereo effect after being processed by the brain visual cortex.
Currently, the 3D display technology comprises a bare eye mode and a glasses mode. FIG. 1 shows a principle of the bare eye mode of 3D display technology. As shown in FIG. 1, a parallax barrier is provided between the display panel and the viewer. Since the parallax barrier comprises light transmission regions and light non-transmission regions alternatively arranged, the left eye of the viewer only can see a left eye picture, and the right eye of the viewer only can see a right eye picture. In this way, the viewer can feel the stereo effect with the bare eyes without stereo glasses.
Currently, the parallax barrier commonly comprises a BM (black matrix) barrier and a liquid crystal barrier. The BM barrier can achieve the 3D display, but cannot switch the display between 2D and 3D. The liquid crystal barrier is an active barrier and can switch the display between 2D and 3D. FIG. 2 shows a structure of the liquid crystal barrier. As shown in FIG. 2, the liquid crystal barrier mainly comprises a first substrate 21, a second substrate 22, and a liquid crystal layer 23 disposed between the first and second substrates 21, 22. A plurality of strip ITO electrodes 24 are arranged and equally spaced from each other on an inner side of the first substrate 21 (toward the liquid crystal 23), and a first polarizer 26 is provided on an outer side of the first substrate 21. A plate ITO electrode 25 is provided on an inner side of the second substrate 22, and a second polarizer 27 is provided on an outer side of the second substrate 22. The polarization direction of the first polarizer 26 is perpendicular to that of the second polarizer 27. In order to ensure liquid crystal molecules of the liquid crystal layer are evenly arranged in a fixed orientation, two polyimide (PI) films are often coated on regions of the inner sides of the first and second substrates which are in contact with the liquid crystal molecules, the friction orientations of the two polyimide films form 90 degrees relative to each other, so that the liquid crystal molecules have a twist angle of 90 degrees without a voltage applied thereon.
Hereafter, it will describe the operation principle of the liquid crystal barrier. When a voltage is not applied on the liquid crystal barrier, the liquid crystal molecules have the twist angle of 90 degrees, therefore, a light is affected by the second polarizer, and a polarization light of the light which is parallel to the polarization direction of the second polarizer enters the liquid crystal layer, passes through the liquid crystal molecules, and reaches the first polarizer. When the light reaches the first polarizer, the polarization direction of the light is parallel to the polarization direction of the first polarizer, and the light can transmit through the first polarizer. Thereby, when there is no voltage applied on the liquid crystal barrier, the light can transmit through the liquid crystal barrier, and in this case, the liquid crystal barrier is operated in the 2D display mode.
When a voltage is applied on the liquid crystal barrier, the liquid crystal molecules corresponding to the strip electrodes are deflected and the orientation thereof generally is parallel to a direction of an electric field. The liquid crystal molecules corresponding to a region beyond the strip electrodes are not deflected. In this case, the light enters from the second polarizer, and the polarization light of the light which is parallel to the polarization direction of the second polarizer enters the liquid crystal layer. The direction of the polarization light is changed after passing through the non-deflected liquid crystal molecules and has a polarization direction parallel to the polarization direction of the first polarizer when reaching the first polarizer and can transmit through the first polarizer.
Contrary, the direction of the polarization light is not changed after passing through the deflected liquid crystal molecules. Therefore, the polarization light has a polarization direction perpendicular to the polarization direction of the first polarizer when reaching the first polarizer and cannot transmit through the first polarizer. As a result, when there is a voltage applied on the liquid crystal barrier, the region of the liquid crystal barrier where the strip electrodes are located is formed as a light non-transmission region, the other region of the liquid crystal barrier beyond the strip electrodes is held as a light transmission region. In this way, a parallax barrier is formed. As a result, the left eye of the viewer only can see the left eye picture, the right eye of the viewer only can see the right eye picture, and the 3D display is achieved by separating the visual pictures of the left and right eyes.
Although the liquid crystal barrier can switch the display between 2D and 3D, it has poor display brightness due to the effect of the polarizer. Furthermore, in the 3D display, the voltage must be applied on the strip electrodes of the liquid crystal barrier all the time, consuming large amounts of energy.